Continuation of a Cooperative Group of Radiation Therapy Research and Clinical Center for the purpose of conductive joint clinical investigations. This group has undertaken clinical trials for other cooperative studies in an endeavor to advance knowledge in the curative and palliative management of cancer. It will be possible, through the collaboration of the radiotherapy centers joined in the Radiation Therapy Oncology Group, to provide an adequate number of patients to answer significant questions in the treatment of cancer, not possible on the basis of the number of patients seen in any one institution. A sophisticated biostatistical center, as an integral part of the Radiation Therapy Oncology Group, is ensuring satisfactory methodology of the studies and aids in establishing an order of priorities for studies which are of the greatest importance and can yield an answer in a reasonable period of time. This group is making possible the collection of long-term data with regard to Radiation complications as well as patient survival. The group is also integrating study programs in cancer with those in other disciplines and enriching training programs in oncology and radiation therapy. This group, by virtue of primary referral of large numbers of patients with potentially curable cancer will be able to supply such patients for interdisciplinary studies in cooperation with the other groups in the clinical investigation branch such as Eastern Cooperative Oncology Group and Central Oncology Group.